What volume of oxygen at N.T.P is needed to cause the complete combustion of 200 mL of acetylene ? Also calculate the volume of carbon dioxide formed.

Explanation

The chemical equation for the combustion of acetylene is
`{:(2C_(2)H_(2),+5O_(2),rarr,4CO_(2)+2H_(2)O),("2 vol.","5 vol",,"4 vol."),("2 mL","5 mL",,"4 mL"):}`
Step I. Calculation of the volume of oxygen needed
2mL of `C_(2)H_(2)` at N.T.P require `O_(2)=5` mL
1 mL of `C_(2)H_(2)` at N.T.P. require `O_(2)=(5)/(2) mL`
`:.` 200 mL of `C_(2)H_(5)` at N.T.P. require `O_(2)=(5)/(2) xx 200` mL = 500 mL
Step II. Calculation of the volume of carbon dioxide formed
2 mL of `C_(2)H_(2)` at N.T.P from `CO_(2)=4` mL
1 mL of `C_(2)H_(2)` at N.T.P form `CO_(2)=(4)/(2) = 2 mL`
`:.` 200 mL of `C_(2)H_(2)` at N.T.P form `CO_(2)=2 xx 200` mL = 400 mL.